Abstract

The Paddyfield Warbler Acrocephalus agricola has recently expanded its breeding range westwards to the western coast of the Black Sea. Although its non-breeding range is known (southern Iran to northern Myanmar), current knowledge on how individual birds migrate and how their routes evolve alongside range expansion processes is very limited. Data from one geolocator deployed on a Paddyfield Warbler at a recently established breeding site in Bulgaria show that this individual retraced the recent range expansion and followed a rather conservative route instead of migrating directly to India. An additional stable hydrogen (δ2H) analysis of feathers from 25 individual breeding birds in Bulgaria that had been grown during their stay in the non-breeding grounds indicated a low degree of migratory connectivity at the non-breeding grounds. Our results provide a first insight into the migration pattern of the Paddyfield Warbler and should stimulate further research on the use of the understudied Indo-European flyway by this species.

Notes

Acknowledgements

František Buben, Dimitar Dimitrov, Martin Marinov, Strahil Peev, Boris Prudík, Christoffer Sjöholm, Martin Sládeček, Matěj Žídek assisted in the field. Yvonne Klaar and Doris Fichte helped with the stable isotope analysis. We thank Adéla Stupková for the painting of the Paddyfield Warbler and her help in the field. We are grateful to anonymous reviewers for their comments on the manuscript. The study was funded by the Czech Science Foundation (project no. 13-06451S). The research was conducted under permissions 574/27.03.2014 and 672/17.03.2016 issued from the Ministry of Environment and Waters of Bulgaria and complies with the current Bulgarian laws.